decontaminate the total volume of concrete with potential surface contamination to a depth of 0.25 inch by processing it through the MPF (U.S. Army, 2000d).
The technical basis for selecting a nominal 0.25-inch scabbling depth is documented in the Environmental Closure Plan Outline and Regulatory Review for USACAP Operations Johnston Island, Johnson Atoll (CH2MHILL, 1998). A 0.25-inch depth is also consistent with the requirements of U.S. law (40 CFR 268.45(a)(1) Table 1, “Alternative Treatment Standards for Hazardous Debris”) and with previous experience in decontaminating radioactive concrete structures. Although 0.25-inch scabbling may be adequate to decontaminate most concrete surfaces in the MDB, agent may have penetrated much further in some places (e.g., along cracks and reinforcing bars and in joints between the floor and walls). A procedure for verifying the absence of agent in hard-to-reach locations has not been established. If agent has seeped into these places, additional concrete will have to be removed.
The JACADS closure schedule is based on removing 0.25 inch of concrete from agent-contaminated surfaces and an MPF utilization rate of 60 percent, or 345 lb/hr. This is based on a permitted burn rate of 575 lb/hr (feed rate of one munitions tray containing 700 lb of material every 73 minutes) (U.S. Army, 2000d). The thick epoxy coating could limit the scabbling rate and affect the closure schedule unless at least 345 lb/hr can be removed. As the furnace can operate at a higher feed rate, there is some built-in contingency. Beyond that, the completion date will slip.
The schedule could also be compromised by the need to decontaminate places in the concrete where agent has penetrated much more than 0.25 inch. Core borings of floors and walls in the MDB might be expected to show how far agent has penetrated into the concrete. However, borings of this type are usually done with diamond-tipped core bits, often with water cooling the cutting edge. The heat and moisture involved in this operation could substantially change the chemical composition of the sample and might vaporize or chemically alter any agent that was present before the sample was taken; as a result, the analytical results for agent values might underreport the amount of agent actually present in the concrete.
Closure operations at JACADS began approximately in January 2001 and are estimated by the Army and WDC to be completed in October 2003, a total of 33 months17 (Bushman, 2001). The closure criteria given in the Facility Closure Plan states as follows (U.S. Army, 2000a):
Closure of JACADS will be accomplished by demonstrating the absence of identified regulated substances or waste-related compounds:
On surfaces within the facility and waste storage areas;
On surfaces and the subsurfaces surrounding the facility and waste storage areas;
On subsurfaces directly beneath the facility, and waste storage areas where necessary;
On or within any other area or structure deemed to be included in the JACADS Closure Campaign (JCC) through the RCRA Facility Assessment (RFA) or other means.
At the time the schedule was developed, there were significant uncertainties, the most important of which was EPA’s failure to agree on the end state for the site in the absence of a decision on end use. The Army and WDC assumed that industrial standards would apply rather than more stringent residential standards. However, this issue has not been settled. Moreover, EPA agreement will be required for RCRA permit modifications C3-050 and C3-051 and any new ones. Failure to obtain approval for any of these modifications will further prolong the closure schedule. The main impetus for completing closure as quickly as possible is the high cost of continued operations (it reportedly costs $331,500 per day for JACADS with a full complement of personnel) (Bushman, 2000).
The initial cost estimate in early 1999 for the JACADS closure program was $70 million to $80 million.18 This estimate was labeled a rough, order-of-magnitude estimate that, because it did not include certain noncontractor charges, was rather optimistic. Another estimate given to the committee in September 1999 was $150 million (Bushman, 1999). The most current estimate is between $200 million and $400 million.19 Final cost estimates for each permit modification can be made only after EPA approval.
The estimate of $200 million to $400 million is based on the assumption that EPA will require only the industrial cleanup standard. If, however, EPA chooses the residential standard, it is estimated that there will be a substantial increase in cost and considerable uncertainty owing to the unknown difficulty of the more rigorous cleaning and the timing of the switch in standards. The timing of a possible switch in standards, particularly if it occurs after completion of the present cleanup, would give rise to an avoidable cost and therefore merits consideration.